No. I.] SENSE-ORGANS OF LUMBRICUS AGRICOLA. 229 



sensory apparatus composed of definite groups of sense-cells 

 whose outer ends pass through the cuticula as sense-hairs and 

 whose inner ends give origin to nerve-fibres which pass directly 

 to the central nervous system and there end freely. 



2. The great number of these sense-organs, their existence 

 over the entire body, their great abundance at the two extremi- 

 ties, and the zones of large ones in such positions as easily to 

 be brought in contact with foreign bodies, accounts for the 

 well known and extreme sensitiveness of Lumbricus. 



3. These epidermal sense-organs were known to Leydig 

 ('65), Schulze, Mojsisovics ('77), Vejdovsky ('84), Ude ('86), and 

 Kulagin ('88), and their presence can be readily demonstrated. 



4. As I have found no isolated nerve-cells in the epidermis 

 of Lumbricus, I am able to account for those described by 

 Lenhossek only on the assumption — which seems to me to be 

 fully warranted by the facts — that he saw the sense-cells of 

 the sense-organs, but failed to recognize the grouping of these 

 cells into organs. 



5. The sense-cells are the only cells with which these fibres 

 are connected. They are therefore the nutrient centers of the 

 sensory fibres and true ganglion cells. 



6. If there is any differentiation in function between sense- 

 organs of different regions, it is not correlated with any pro- 

 nounced differences in structure. 



7. The efferent nerve-fibres which pass from the central 

 nervous system to the epidermis are not in continuity with any 

 cellular element of the latter. They form a subepidermal net- 

 work which gives rise to intraepidermal nerve-fibres which end 

 freely between the epidermal cells. 



Ann Arbor, Mich., 

 June 18, 1894. 



